feat(legal): wire recurrent-payments document + restore footer link

Backend now serves a dedicated recurring-payments legal document, so:
- Add adminLegalPagesApi.get/updateRecurrentPayments and infoApi.getRecurrentPayments
  (+ InfoVisibility.recurrent).
- AdminLegalPages: new 'Рекуррентные платежи' editor tab (DocumentEditor now driven
  by a DOCUMENT_API dispatch map instead of privacy/offer ternaries).
- PublicLegal: add 'recurrent' doc; add public /recurrent-payments route.
- Re-add the recurrent link to the login LegalFooter (was removed pending backend).
- i18n: admin.legalPages.tabs.recurrent for ru/en/fa/zh (footer.recurrent already existed).

type-check, eslint, prettier and build all pass.

src/locales/en.json

@@ -4181,6 +4181,7 @@
       "tabs": {
         "privacy": "Privacy",
         "offer": "Offer",
+        "recurrent": "Recurring Payments",
         "rules": "Rules",
         "faq": "FAQ"
       },

src/locales/fa.json

@@ -4006,6 +4006,7 @@
       "tabs": {
         "privacy": "حریم خصوصی",
         "offer": "پیشنهاد",
+        "recurrent": "پرداخت‌های تکراری",
         "rules": "قوانین",
         "faq": "FAQ"
       },

src/locales/ru.json

@@ -4726,6 +4726,7 @@
       "tabs": {
         "privacy": "Политика конф.",
         "offer": "Оферта",
+        "recurrent": "Рекуррентные платежи",
         "rules": "Правила",
         "faq": "FAQ"
       },

src/locales/zh.json

@@ -4005,6 +4005,7 @@
       "tabs": {
         "privacy": "隐私",
         "offer": "条款",
+        "recurrent": "定期付款",
         "rules": "规则",
         "faq": "FAQ"
       },